Process for producing lecithin products from soapstocks



Feb. 7, 1961 B. H. THURMAN 2,970,910

PRocEss FOR PRonucING LECITHIN PRoDucTs FROM soAPsTocKs Filed July 14. 1955 United States Patent l PROCESSFOR PRODUCIN G LECITHIN PRODUCTS FROM SUAPSTOCKS Benjamin H. Thurman, New York, N.Y., assiguor to tBenjamin=Clayton,doing business under the fictitious name and style of` Refining, Unincorporated Filed July 14, 1955, Ser. No. 521,975

13 `:Claims 4(CIL 99-2) `This invention `relates to the production of `lecithin products `obtainable i by :acidulation of certain soapstocks. It will be particularly exemplified as concerns `aprocess of ,refining a crude vegetable oil by use of a non-saponfying alkali toproduce a soapstock which, when acidulated inaccordancewith the invention, yields a nutritive lecithin` product or phosphatidic product excellently suited asia 4feed additive.

Crude glyceride oils containgunrlike materials known as phosphatides `which are of value if they can be recovered andV if they are not degraded `whenthe oil is `refined` For example, crude vegetable oils ,contain high nutritive phosphatides which `heretofore have been largely degraded or destroyed by use ofreiining techniques which `convert-the `phosphatides .to soaps, choline, `trimethylamne `and `other `intermediate products. For examplancrude,oilsreiined with `caustic soda yield `soap- StOlksin which :the phosphatides `have been attackedand largely: decomposed. All such soapstocks containing degraded or .decomposed .phosphatides have .little value, beingymerely a source ,of low-grade fatty `acids .when treated'with large excesses .of sulfuric acid to split the soaps aand `char the :phosphatides and other gum-like substances. :Such a processinvolves boilingfor many hours and consumption of acid far in excess ofthat required to neutralize the excess caustic soda `and convert the soapsto fatty acids. .1;Itis1an object of the present invention -to refine crude glycerideoils insuch way as to produce a valuable lecithin :.product. `In thisconnection, the invention includes mixingithe .crudeoil with a non-saponifying alkali, such asfnodaaashggand .uniquely processing the resulting soapstock ttor produce a .lecithin product. By a` non-saponifying allkli,as the tei-mds herein used, I have reference to ashun-.volatile alkali, Asuchtas soda Aash, sodium l bicarbonate; sodium sesquicarbonate, or disodium phosphate, which is a mild `alkali vas concerns any attack onytri- `g-lycerides t and phosphatides` and which does `not saponify `substantial.:amounts ofthe oil during the refining operation.

. tittgjis ta' further objectof the-invention fto acidulate soap- 'stocksf resulting .from the `refining of crude glyceride oils withciamonfsaponifying alkali, `the acidulation involving 'adding'onlyi-enoughmineral acid -to lower the --pH `to .belowal-S :and usually enough Vto neutralize any excess alkalifandiconvert the soaps into fatty-acids .and corre- 2,970,91 Fatented Feb. 7, 1961 `2 poses, the dried Aproductbeing uid at normal tempera. tures.

`:Further.objectsand advantagesiof vthe invention Awill beevident Ato those skilled in the art from the following description of exemplary embodiments, two of which are schematically `illustrated in the accompanying drawing, in which:

Fig. 1 is a `schematic iiow diagram of a. process of:the inventori inwhich the acidulated soapstock canibe separatediby gravity; and

Fig. 2 is a schematic flow diagram illustrating a process in .which the acidulated soapstock is continuously `separated.

The soapstocks with which `this invention is concerned are those resulting from the refining of crude'glyceride oils by non-saponifying, non-volatile alkalis so that the soapstocks still contain the indigenous phbsphatides substantiallyunmodified. Hereinafter, soda ash soapstocks will be exemplified. Those resulting from the usual sodaash processes or so-called low-excess soda ash refining process are good sources of valuable lecithinprod'ucts. Suchlow-excess soda ash processes employ soda ash in amount not more than about three times that required `to neutralize the free fatty acids of the crude oil.

In accordance with `the invention, such soapstock is acidulated with only suflicient mineral acid largely to convert any excess soda ash to sodium sulfate,` thesoaps to `fatty acids and sodium sulfate, and the soda ash phosphatide complex to free phosphatides. Upon settling or centrifuging, a minor portion or layer of aqueous ma terial will separate, leavinga majorrportion or layerof a Vlecithin `product comprising free oil, fatty acids and hydrated phosphatide. Most of the sodium sulfate .and other inorganici salts will appear largely in the separated aqueous material. Any salts in the remaining lecithin product can be washed therefrom or can be permitted to 'spending salts. "Arsmall amount of aqueous material is "the, seeds, beans, or` other source material. A-further object-ofthe ,-invention'is to dry such alecithin product remain therein as the small amount thereof is unobjectionable as a component of feeds.

Any relatively concentrated mineral .acid can be used to` acidulate the soapstock, typically sulfuric, phosphoric or hydrochloric acid. Sulfuric acid is preferred, usually of a concentration between 98% and 10%, usually about `25%. The amount of acidwill desirably be such asto reduce the pH of the soapstock to about pH 5-7. `Sometimesa pH slightlyabove 7 but below 8 is practical and produces a separated fatty layer containing somewhat more water `than if the pH is within the range of 5-,7. Addition of acids to reduce the pH to a value in the neighborhood of pH 5 is particularly desirable but use of larger amounts of acid `as would char the phosphatides is tobe avoided. The consumption of acid depends upon the free fatty acid content of the crude oil but `is comparatively small, particularly when acidulating soapstock from a low`excess soda ash refining.

r The fatty material orV lecithin product which separates from the aqueous material contains the phosphatides in substantially the same state and amount as in the crude oil. It can be shipped economically because of its cornparatively low water and high T.F.A. contents. The product canbe readily pumped into and from a tank car or from oneV portion of a refinery to another.

."This lecithin product may be added directly to products used in animal feeding or may be dried before being added to such products. Particularly desirable results arisefrom mixing thelecithin or concentrated-phosphatide product with meals .produced when the source oill or;other glycerde oil is separated from the seeds or beans by solventA extraction orby pre-pressingand solvent Aextraction. Ihe phosphatide concentrate added toethe meal. yespecially vmealfrom` solventiextraction, ladds to1thefnu tritive value .becausepf-ithefncreasedqtm `andiphosphatide content of the concentrate. Additionally, the color of the meal is improved. Furthermore, the phosphatide concentrate or lecithin product has adhesive tendencies which facilitate pelletizing and eliminate dusting when mixed with meal.

The dried lecithin product often has a fruit-like odor and at room Vtemperature is usually still a liquid product. It will typically contain not more than a small amount of residual water, usually under 1%. Its phosphorous content (P) will usually be in the neighborhood of 0.8 to 3.0%. Acetone insolubles (phosphatides) will be in the neighborhood of 30-60%. The T.F.A. content would usually be about Lt5-80%, all of the aforesaid percentages being by weight.

. Any ratio of phosphatide product to meal will improve the nutritive values. Excellent results have been obtained by adding 0.5-5.0% of the phosphatide product to the meal. Feeding tests show much faster growth of steers on a diet of this type as compared with the meal without the product.

Fig. 1 diagrammatically illustrates a practice of the invention on a commercial scale. The seeds or beans are delivered to a conventional pressing or extracting apparatus producing a crude glyceride oil and a residual meal, as shown. A non-saponifying, non-volatile alkali is mixed with the crude oil either continuously or batchwise in a mixer 12. rl`he oil and alkali may be preheated in heaters 13 and 14, if desired, or may be heated during mixing in the mixer I2. Alternatively, or in addition, the mixture may be heated before being separated, as sug- Y gested by a heater 15. The numeral 18 indicates any con- Yventional separator operating in a batch or continuous manner and which produces a refined oil, indicated by arrow 19, and a soapstock, indicated by arrow 20. The refined oil may be re-relined by use of caustic soda to improve its color, as is well known in the art. No novelty is claimed in the instant process as concerns the steps per se thus far described with reference to Fig. 1 as these steps are well known in the art of refining crude glyceride oils. It is essential to the invention, however, that a non-saponifying alkali be employed so that the separated soapstock will contain the indigenous phosphatides of the oil in substantially their original form, as distinct from being substantially degraded, reacted or destroyed by the alkali refining agent.

Atypical low excess soda ash soapstock will have the Vfollowing composition: 20-45% water (most commonly 25-33%); 10-20% free oil, dry basis; and 3045% I`.F.A. ASuch soapstocks can be acidied as produced. However, it isusuallyV better if thel soapstock contains about S0-75% water when acidulatcd. As the soapstocks often contain less than this amount of water, it is sometimes desirable to add additional water to the soapstock, up to its own weight in some cases, as suggested by the', arrow 21.V

In Fig. 1, the soapstock is delivered alternately to large vessels 25, either with or without heating in a heater 26.

The aforesaid proportions of mineral acid are mixed alternately with the soapstock batches in the containers 25, the mixture being heated or cooled by a heat-exchange coil 27 in each vessel. After mixing, Athe mass is perinitted Vto settle for a time varying from a few minutes to ,several hours. An aqueous layer will settle, leaving a supernatant fatty layercomprising the lecithin products of the invention.VV YThe layerof aqueous material can first bewithdrawn from the containers 25 as suggested by the numeral 29leaving the lecithin product therein.

Separating temperaturespare desirably in the range of froml about F. up to 300 F. The usual temperature for gravitational orv centrifugal separation is Vabout '160-210 F. and it is never desired to employ temperatures and times of treatment thatwould split the gums or phosphatides of vthe lecithin product., Temperatures above-210l F. would be normally used only for suppleniental'puiposes, such as the detoxification of gossypol to be described, and if used wouldlbe accompanied by suf-` cient pressure to prevent vaporization of water.

The lecithin product can be withdrawn alternately from the containers 25 to produce a continuous stream, which may be washed in a washer 32 or by-passed therearound, as indicated at 33, if washing is not desired. Such a water wash will remove residual salts, typically sodium sulfate, albeit such washing is usually not essential if the lecithin product is to be incorporated in feeds.

The washed or unwashed lecithin product can be delivered through a valve 35 and a heater 36 to a mixer 38 for mixing with the meal from the pressing or extracting apparatus 10, producing a high nutritive feed product. In many instances, however, it is desirable to close the valve 35 and open a valve 39 to deliver the Washed or unwashed lecithin product to a dryer 40 where it is dried under vacuum before being delivered to the mixer 38. Drying at temperatures of about 180 220 F. under a vacuum of about 26-291/2 inches of mercury will be found quite satisfactory. The lecithin product may be dried by the same equipment and in substantially the same manner as employed for the drying of hydrated lecithins or phosphatides for the production of commercial lecithin, e.g., heating in vacuo to a temperature of 15G-210 F.

It will be apparent that all of the steps suggested in Fig. 1 can be performed batchwise in a single vessel, if desired. Alternatively, many of the steps can be performed in separate vessels in a continuous or semicontinuous process.

In Fig. 2 is suggested Va continuous acidulation in which the soapstock is continuously supplied to a mixer 50 by any suitable pumping system, not shown. Similarly, aV continuous stream of mineralV acid is supplied by a vproportiolning pump, not shown, the mineral Vacid being delivered to the mixer 50 as suggested by the numeral 51. The mixture then ows, with or without temperature adjustment in a heat exchanger 52, to a. separator 54 which may be a conventional centrifuge discharging streams of the aqueous material and lecithin product. The remaining equipment in Fig. Zis similar to that shown in Fig. 1.

The process greatly reduces the water. content Vof the soapstock. As compared with the original soapstock, which normally may have a water content of about 35-. 45% or more, the water content of the separated lecithin product will usually be less than 30% and often less .than 20%. Even lower water contents may be obtained .by heating under pressures of approximately 5-50 p.s.i. to corresponding temperatures of about 22S-300 YF. This treatment causes further amounts of emulsied water to be released and can produce a product contain-ing no more than about 10-15 water.

Such higher temperatures, preferably appliedduring .or after the initial separation of the aqueous material from the acidied soapstock, are of particular value when acidifying cottonseed soapstock high in free gossypol. West Texas and many pre-pressed or solvent-extracted cottonseed oils contain substantial amounts of free gossypol, as do the soapstocks obtained therefrom when refining with non-saponifying alkali such as soda ash. Such free gossypol is toxic to certain animals and it may `be necessary to reduce the gossypol content of many Yof these soapstocks before they can be used as feeds. Heating the soapstocks to temperatures of about 285"` F. C.) for about 1 hour will substantiallyV detoxify the soapstock, albeit higher temperatures applied for shorter times will also be effective. The initial free gossypol, dry basis, before acidification and heating of the soapstock, will usually vary from 2-8% or even2 410%, while the free gossypol after acidification and heating will be below 0.25% and thus entirely unobjectionableinthe feed product. Specifically, if the present :process is used in vtreating vsoda ash Vsoapstock` from cottonseed oil highinfree gossypol, the soapstock mayN be; heatedto a temperature of about 285-350 F. for

respective times of 1 hour to 10 minutes in the presence..`

of or after separationof the aqueous material that separates when the pH,is adjusted to about 5. Commonly.

Vsuch temperature may be applied in the heaters 36. lf

such temperatures are applied in the containers 25 of temperatures.

In no instance, howevendoes the present inventionf contemplate the use of such high temperatures and such largeamounts of water as to split the gums or phos phatidic materials present- -in or from the original crude oil.- Due to the relatively low water content of the soapstock and to the fact that temperatures in the present process are always below 350 F., the present process does `not involve any substantial splitting of the gums under the action of heat and `pressure in the presence of` large amounts of water.

While the process can be practiced in numerous ways,

the following examples illustrate typical results.

Example A soda ash soapstock containing 40% moisture and produced from the refining of a crude soya oil with soda ash was mixed with a 25% sulfuric acid solution in sufficient quantity to reduce the pI-I of the soapstock" Io approximately 5f Eight parts of the acid was required for 100 parts by weight (dry basis) of the soda ash soapstock. `A `fatty layer separated and was` liquid, at temperatures of 180200 F. The fatty layer of-p lecithin product `had a water content of 24%. After being dried in vacuo at 70 C., the dried product was a phosphatideconcentrate, fluid at room temperature, containing 0.44% water, 2.11% phosphorous, 53.4% acetone in solubles and 66.8% T.1.`A.

Y `ExamplelZ To 125 parts of a low excess soda ash cottonseed soapstock was initially mixed 65 parts by weight of warm Water. The hydrated soapstock was acidified with 8 parts,`

of a 25% aqueous sulfuric acid solution, which brought `the mixture toapH of 5. The f atty layer or lecithinV productwas settled rat atemperature of 18S-200 F withdrawn and dried in vacuo at 160 F. The dried;

product, fiuid at room temperature, contained 0.44% water, 1.21% phosphorous, 49.6% acetone in solubles (phosphatides), 73.6% T.F.A. (of` which about 33% was free fatty acids), and 0.75% free gossypol, dry basis. The gossypol content of the soapstock before treatment was 2.0%, dry basis.

Example 3 In this instance, 150 parts of corn oil soapstock, resulting from a soda-ash refining off crude corn oil was mixed With 150 parts `by weight of hot water. To bring the pH'ofthe soapstock to a value of pH` 5 required 83 parts `by weight of a 25% sulfuric acid solution. Separa- `tion was in a steam bath for 4-6 hours after which the fatty layer was withdrawn and dried in vacuo. The dried product was liquid at room temperature and contained 0.3% water, 1.3% phosphorous, 45.2% acetone insolubles (phosphatides) and 53.6% T.F.A.

Various changes and modifications will be apparent-to those skilled in the art and fallY within the scope of the appended claims.

I claim as my invention:

isisoda ash and in which the amount of mineral acid is` adjusted to reduce. the pH of the soapstock to about pH 5.

4.` A process for refining crude glyceride oils containing nutritive phosphatides, which process includes` `the steps of: mixing such glyceride oil with a` non-saponifying alkali and separating the mixture into a refined oil and a soapstock containing` said phosphatides; treating said soapstock with a mineral acid at a temperature and pressure insufficient substantially to split said phosphatides, the amount of mineral acid being only sufficient to bring the pH of the soapstock to a value of about pH 5-8; separating the acidified soapstock into an aqueous material and a lecithin product `comprisingfree oil, fatty acids and hydrated phosphatides from the glyceride oil; and: drying the lecithin product to produce a dried lecithin product containing said phosphatides in nutritive state.

5. In the process of refining glyceride oils produced from seeds or beans by processes involving the produc- :tion of a residual meal and a crude oil containing free fatty acids and nutritive phosphatides, the steps of: mixingsaid crude oil with a non-saponifying alkali; separatingthe mixture into an oil containing substantially none.

of `said free fatty acids and a soapstock containing said nutritive phosphatides largely in their original state;`

6. Ajprocess as defined in claim 5 including the ste'pl o f .drying said, lecithin product.` under Vacuum` before adding to said meal.

7. A process for refining crude glyceride oils containl ing free fatty acids and nutritive phosphatides, which `1. A process for refining crude glyceride oils containinsufficient substantially to splitor char said phosphatides,

process includes the steps of: mixing the glyceride oil with soda ash in amount not substantially more than required to convert said free fatty acids into soaps; separating the mixture into a refined oil and a soapstock containing said phosphatides in substantially their original state; mixingwith the soapstock a mineral acid in amount sufficient only to reduce the pH of the soapstock toabout pH 5-8 and insufficient to char the phosphatides of the soapstock; separating Ythe acidified soapstock into an aqueous material anda lecithin product; and drying such lecithin product.

8.Y A process as defined in claim 7 in which said dried lecithin product is added to a glyceride oil meal to form a feed product.

9. In the process of refining glyceride oils produced from seeds or beans as the source material by processes involving the production of a residual meal and a crude oil containing free fatty acids and nutritive phosphatides,

the steps ofz Mixing said crude glyceride oil with sodaV ash in amount not substantially more than three times that required to neutralize said free fatty acids; separating from the mixture a soapstock containing said nutritive phosphatides; treating said soapstock with a mineral acid at a temperature insufiicient substantially to split said phosphatides, the amount of said mineral acid being only sufficient tobring the pH of the soapstock to a value of 7 Y about pH -8; separating the acidied soapstock into an aqueous material and a lecithin product comprising free oil, fatty acids and hydrated phosphatides from the glyceride oil; and mixing said lecithin'product with sai meal to form an animal feed product.4 v

10. In the process of refining glyceride oils produced from seeds or beans as the source material by processes involving the production of a residual meal and a crude oil containing free fatty acids and nutritive phosphatides, the steps of: mixing said crude glyceride oil with soda ash in amount not substantially more than'requircd to convert said free fatty acids into soaps; separating from the mixture a soapstock containingk said nutritive phosphatides; adding to the separated soapstock an amount of water to bring the water content of such soapstock to about 50-75%; treating the resulting soapstock/with a' mineral acid at a temperature insufficient substantially to split said phosphatides, the amount of said mineral acid being only sufiicient to bring the pH of the soapstock to a value of about pH 5,-8; separating the acidified soap- Stock into an aqueous material and a lecithin product comprising free oil, fatty acids and hydrated phosphatides from the glyceride oil; and mixing said lecithin product with said meal to form an animal feed product.

11. A process for producing a nutritive phosphatidic product from crude glyceride oils containing nutritive phosphatides, which process includes the steps of: mixing such glyceride oil with a non-saponifying alkali and separating the mixture into a refined oil and a soapstock containing said phosphatides; mixing a mineral acid with said soapstock under conditions of temperature` and.

pressure insufficient substantially to split or char said phosphatides, the amount of mineral acid being 4only sufficient to bring the pH of the soapstock to a value of about'pH 5-8; and separating the acid treated soapstock into a volume of'aqueous material landa volume of a phosplhatidic product comprising about 30-60% by weight of acetone insoluble phosphatides inY substantially `the same state and amount as in'said crude oil before such oil was mixed with said alkali. Y, n i

`12. A process for producing a nutritive phosphatidic product from a crudeY glyceride oil containing nutritive phosphatides and free fatty acids?, which process includes the steps of: mixing such glyceride oil with an amount ofsoda ash no more than three times that required to neutralize said free fatty acids of suchoil; `separating fromtheiresulting mixture a soapstock containing said phosphatides as arsoda ash phosphatide complex, a small reduce its lpH to a value between about pH 5 and pH 8 under conditions of temperature and pressure insufficient to `vsubstantially split or char said phosphatides, the amount of said mineral acid being only sufficient to largely convertsaid small amount of soda ash `to sodium sulfate, the sodium soaps to fatty acids and sodium sulfate, and the soda ash phosphatide complex to free phosphatides; and separating the acid treated soapstock into a volume ofaqueous material and a volume of a phosphatidic product containing said nutritive phosphatides in substantially the same state and amount as in said crude glyceride oil.

13. A process for refining crude glyceride oils containing nutritive phosphatides, which process includes the steps of: mixing such glyceride oil with a non-saponifying alkali and separating the mixture into a refined oil andy a soapstock containing said phosphatides; adding water to the separated soapstock to bring the water content thereof to about -75%; treating the resulting soapstock with a mineral acid at a temperature and pressure insufiicient substantially to split or char said phosphatides, the amount of mineral acid being only sufficient to bring the pH of the soapstock to a value of about pH Sk8; and separating the acid treated soapstock into a volume of aqueous material and a volume of a lecithin product comprising free oil, fatty acids and hydrated phosphatides from the glyceride oil still in nutritive state. t

References Cited in the file of this patent Markley: Soybeans and Soybean Products, vol. 1I', 1951, pp. 646 and 892.

Ault et al.: 4, 5 and 19.

Chemurgic Digest, 'December 1954, pp. 

1. A PROCESS FOR REFINING CRUDE GLYCERIDE OILS CONTAINING NUTRITIVE PHOSPHATIDES, WHICH PROCESS INCLUDES THE STEPS OF: MIXING SUCH GLYCERIDE OIL WITH A NON-SAPONIFYING ALKALI AND SEPARATING THE MIXTURE INTO A REFINED OIL AND A SOAPSTOCK CONTAINING SAID PHOPHATIDES, TREATING SAID SOAPSTOCK WITH A MINERAL ACID AT TEMPERATURES AND PRESSURE INSUFFICIENT SUBSTANTIALLY TO SPLIT OR CHAR SAID PHOPHATIDES. THE AMOUT OF MINERAL ACID BEING ONLY SUFFICIENT TO BRING TH PH OF THE SOAPSTOCK TO A VALUE OF ABOUT PH 5-8, AND SEPARATING THE ACID TREATED SOAPSTOCK INTO A VOLUME OF AQUEOUS MATERIAL AND VOLUME OF A LECITHIN PRODUCT COMPRISING FREE OIL, FATTY ACIDS AND HYDRATED PHOSPHATIDES FROM THE GLYCERIDE OIL STILL IN NUTRITIVE STATE. 